Alternate instrument removal

ABSTRACT

Minimally invasive robotic surgical instruments and related methods are disclosed. A surgical instrument includes an interface fitting that couples a proximal chassis of the instrument with a holding fixture of a robotic manipulator. A securing feature releasably prevents relative axial sliding between the interface fitting and the chassis. In response to binding of the surgical instrument within a minimally invasive surgical site so as to inhibit removal of the surgical instrument from the surgical site and inhibit disengagement of the interface fitting from the holding fixture, the securing feature can be released to allow relative axial sliding between the interface fitting and the chassis, thereby allowing the holding fixture and the interface fitting to be separated from the rest of the surgical instrument and repositioning of the robotic manipulator out of the way.

BACKGROUND

Minimally-invasive surgical techniques are aimed at reducing the amountof extraneous tissue that is damaged during diagnostic or surgicalprocedures, thereby reducing patient recovery time, discomfort, anddeleterious side effects. As a consequence, the average length of ahospital stay for standard surgery may be shortened significantly usingminimally-invasive surgical techniques. Also, patient recovery times,patient discomfort, surgical side effects, and time away from work mayalso be reduced with minimally-invasive surgery.

A common form of minimally-invasive surgery is endoscopy, and a commonform of endoscopy is laparoscopy, which is minimally-invasive inspectionand surgery inside the abdominal cavity. In standard laparoscopicsurgery, a patient's abdomen is insufflated with gas, and cannulasleeves are passed through small (approximately one-half inch or less)incisions to provide entry ports for laparoscopic instruments.

Laparoscopic surgical instruments generally include an endoscope (e.g.,laparoscope) for viewing the surgical field and tools for working at thesurgical site. The working tools are typically similar to those used inconventional (open) surgery, except that the working end or end effectorof each tool is separated from its handle by an extension tube (alsoknown as, e.g., an instrument shaft or a main shaft). The end effectorcan include, for example, a clamp, grasper, scissor, stapler, cauterytool, linear cutter, or needle holder.

To perform surgical procedures, the surgeon passes working tools throughcannula sleeves to an internal surgical site and manipulates them fromoutside the abdomen. The surgeon views the procedure from a monitor thatdisplays an image of the surgical site taken from the endoscope. Similarendoscopic techniques are employed in, for example, arthroscopy,retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy,sinoscopy, hysteroscopy, urethroscopy, and the like.

Minimally-invasive telesurgical robotic systems are being developed toincrease a surgeon's dexterity when working on an internal surgicalsite, as well as to allow a surgeon to operate on a patient from aremote location (outside the sterile field). In a telesurgery system,the surgeon is often provided with an image of the surgical site at acontrol console. While viewing a three-dimensional image of the surgicalsite on a suitable viewer or display, the surgeon performs the surgicalprocedures on the patient by manipulating master input or controldevices of the control console. Each of the master input devicescontrols the motion of a servo-mechanically actuated/articulatedsurgical instrument. During the surgical procedure, the telesurgicalsystem can provide mechanical actuation and control of a variety ofsurgical instruments or tools having end effectors that perform variousfunctions for the surgeon, for example, holding or driving a needle,grasping a blood vessel, dissecting tissue, or the like, in response tomanipulation of the master input devices.

Non-robotic linear clamping, cutting, and stapling devices have beenemployed in many different surgical procedures. For example, suchdevices can be used in a lower anterior resection (LAR) to resect acancerous or anomalous tissue from the proximal (upper) two-thirds ofthe rectum. In an LAR, however, it is not uncommon for the surgicalinstrument to be fully inserted (i.e., the instrument shaft becomesfully inserted) during the procedure. And in some instances, a highforce clamping instrument such as a stapler device may become clamped ontissue and unable to unclamp. When both of these situations occursimultaneously (i.e., instrument fully inserted and the end effectordevice unable to unclamp), it may be necessary to decouple the surgicalinstrument from the robotic system to effectively deal with thesituation. With existing instruments and robotic systems, however, itmay be difficult if not impossible to decouple the surgical instrumentfrom the robotic system in such a scenario.

BRIEF SUMMARY

Surgical instruments for use with a robotic manipulator of a minimallyinvasive surgical system and methods for using a surgical instrumentwith a robotic manipulator of a minimally invasive surgical system aredisclosed. The disclosed surgical instruments and methods can, forexample, ensure that a surgical instrument can be decoupled from arobotic manipulator when an end effector clamping device is unable to beunclamped from patient tissue while the surgical instrument is fullyinserted into the patient. By decoupling the surgical instrument fromthe robotic manipulator, the robotic manipulator can be repositioned outof the way of efforts to deal with the bound surgical instrument.

Thus, in a first aspect, a method is provided for using a surgicalinstrument with a robotic manipulator of a minimally invasive surgicalsystem. The method includes providing a surgical instrument thatincludes an elongate shaft extending along an axis between a distal endand a proximal end, a chassis disposed at the proximal end, and an endeffector disposed at the distal end. The chassis includes a frame, aninterface fitting demountably coupled with the frame via slidingengagement along the axis between the frame and the interface fitting,and a securing feature that is operable to prevent relative axialsliding between the interface fitting and the frame. The chassis ismounted onto a holding fixture of the robotic manipulator by engaging amounting feature of the interface fitting with a complementary-shapedmounting feature of the holding fixture. And the end effector isarticulated within a minimally invasive surgical site. In response tobinding of the surgical instrument within the surgical site so as toinhibit removal of the end effector and shaft from the surgical site,and so as to inhibit disengagement of the mounting feature of theinterface fitting from the mounting feature of the holding fixture, thesecuring feature is released so as to allow relative sliding between theinterface fitting and the frame. The frame, shaft, and end effector ofthe surgical instrument are demounted from the interface fitting of thesurgical instrument and the holding fixture of the robotic manipulatorby moving the interface fitting relative to the frame along the axis.

The above method can include additional acts. For example, the methodcan include sliding the interface fitting into engagement with theframe. And the method can include securing the interface fitting inengagement with the frame via the securing feature.

In many embodiments, the securing feature includes a removable fastener.For example, the securing feature can include a plurality of removablefasteners.

In many embodiments, the interface fitting and the frame includecomplementary-shaped interfacing features. For example, thecomplementary interfacing features can include a slot extending alongthe axis. And the complementary-shaped interfacing features of theinterface fitting and the frame can include two slots extending alongthe axis, with the slots disposed on opposite sides of the frame. Forexample, the frame can include the two slots and the interface fittingcan include two protruding mounting features extending along the axis.And each of the protruding mounting features can include a flangeextending along the axis.

In another aspect, a surgical instrument is provided for use with arobotic manipulator of a minimally invasive surgical system, the roboticmanipulator having a holding fixture. The surgical instrument includesan elongate shaft extending along an axis between a distal end and aproximal end, a chassis disposed at the proximal end, and an endeffector disposed at the distal end. The chassis includes a framesupporting the shaft, an interface fitting demountably coupled with theframe via sliding engagement along the axis between the frame and theinterface fitting, and a securing feature releasably preventing relativeaxial sliding between the interface fitting and the frame. The interfacefitting has a mounting feature receivable by the holding fixture of therobotic manipulator so as to mount the instrument thereon. The endeffector is articulatable relative to the shaft so as to manipulatetissue within a minimally invasive surgical site. The securing featureis configured for releasing in response to binding of the surgicalinstrument within the surgical site, the binding inhibiting removal ofthe end effector and shaft from the surgical site and disengagement ofthe mounting feature of the interface fitting from the holding fixture.Releasing the securing features allows relative sliding between theinterface fitting and the frame so as to promote demounting of theframe, shaft, and end effector of the surgical instrument from theinterface fitting of the surgical instrument and the holding fixture ofthe robotic manipulator by moving the interface fitting relative to theframe along the axis.

In many embodiments, the securing feature includes a removable fastener.For example, the securing feature can include a plurality of removablefasteners.

In many embodiments, the interface fitting and the frame includecomplementary-shaped interfacing features. For example, thecomplementary interfacing features can include a slot extending alongthe axis. And the complementary-shaped interfacing features of theinterface fitting and the frame can include two slots extending alongthe axis, with the slots disposed on opposite sides of the frame. Forexample, the frame can include the two slots and the interface fittingcan include two protruding mounting features extending along the axis.And each of the protruding mounting features can include a flangeextending along the axis.

The interface fitting can have a u-shaped configuration that interfaceswith the frame on three sides of the frame. And the u-shaped interfacefitting can be received within two slots in the frame disposed onopposite sides of the frame. The securing feature can include tworemovable fasteners, each of the removable fasteners coupling with a nutretained by the frame.

For a fuller understanding of the nature and advantages of the presentinvention, reference should be made to the ensuing detailed descriptionand accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a minimally-invasive robotic surgery systembeing used to perform a surgery, in accordance with many embodiments.

FIG. 2 is a perspective view of a surgeon's control console for arobotic surgery system, in accordance with many embodiments.

FIG. 3 is a perspective view of a robotic surgery system electronicscart, in accordance with many embodiments.

FIG. 4 is a simplified diagrammatic illustration of a robotic surgerysystem, in accordance with many embodiments.

FIG. 5A is a front view of a patient-side cart (surgical robot) of arobotic surgery system, in accordance with many embodiments.

FIG. 5B is a front view of a robotic surgical tool.

FIG. 6 is a perspective view of an interface fitting coupled with aframe of a proximal chassis of a robotic surgical tool, in accordancewith many embodiments.

FIG. 7 is an exploded perspective view of components of FIG. 6.

FIG. 8 is a perspective view of a robotic surgical tool and interfacefitting assembly coupled to a robotic manipulator of a minimallyinvasive surgical system, in accordance with many embodiments.

FIG. 9 is an exploded perspective view of components of FIG. 8 andillustrates decoupling of the robotic surgical tool from the roboticmanipulator via the removal of the interface fitting, in accordance withmany embodiments.

FIG. 10 is a simplified block diagram of a method for using a roboticsurgical tool with a robotic manipulator of a minimally invasivesurgical system, in accordance with many embodiments.

DETAILED DESCRIPTION

In the following description, various embodiments of the presentinvention will be described. For purposes of explanation, specificconfigurations and details are set forth in order to provide a thoroughunderstanding of the embodiments. However, it will also be apparent toone skilled in the art that the present invention can be practicedwithout the specific details. Furthermore, well-known features may beomitted or simplified in order not to obscure the embodiment beingdescribed.

Minimally-Invasive Robotic Surgery

Referring now to the drawings, in which like reference numeralsrepresent like parts throughout the several views, FIG. 1 is a plan viewillustration of a Minimally-Invasive Robotic Surgical (MIRS) system 10,typically used for performing a minimally-invasive diagnostic orsurgical procedure on a Patient 12 who is lying down on an Operatingtable 14. The system can include a Surgeon's Console 16 for use by aSurgeon 18 during the procedure. One or more Assistants 20 may alsoparticipate in the procedure. The MIRS system 10 can further include aPatient-Side Cart 22 (surgical robot), and an Electronics Cart 24. ThePatient Side Cart 22 can manipulate at least one removably coupled toolassembly 26 (hereinafter simply referred to as a “tool”) through aminimally-invasive incision in the body of the Patient 12 while theSurgeon 18 views the surgical site through the Console 16. An image ofthe surgical site can be obtained by an endoscope 28, such as astereoscopic endoscope, which can be manipulated by the Patient SideCart 22 so as to orient the endoscope 28. The Electronics Cart 24 can beused to process the images of the surgical site for subsequent displayto the Surgeon 18 through the Surgeon's Console 16. The number ofsurgical tools 26 used at one time will generally depend on thediagnostic or surgical procedure and the space constraints within theoperating room among other factors. If it is necessary to change one ormore of the tools 26 being used during a procedure, an Assistant 20 mayremove the tool 26 from the Patient-Side Cart 22, and replace it withanother tool 26 from a tray 30 in the operating room.

FIG. 2 is a perspective view of the Surgeon's Console 16. The Surgeon'sConsole 16 includes a left eye display 32 and a right eye display 34 forpresenting the Surgeon 18 with a coordinated stereo view of the surgicalsite that enables depth perception. The Console 16 further includes oneor more input control devices 36, which in turn cause the Patient-SideCart 22 (shown in FIG. 1) to manipulate one or more tools. The inputcontrol devices 36 can provide the same degrees of freedom as theirassociated tools 26 (shown in FIG. 1) so as to provide the Surgeon withtelepresence, or the perception that the input control devices 36 areintegral with the tools 26 so that the Surgeon has a strong sense ofdirectly controlling the tools 26. To this end, position, force, andtactile feedback sensors (not shown) can be employed to transmitposition, force, and tactile sensations from the tools 26 back to theSurgeon's hands through the input control devices 36.

The Surgeon's Console 16 is usually located in the same room as thepatient so that the Surgeon may directly monitor the procedure, bephysically present if necessary, and speak to an Assistant directlyrather than over the telephone or other communication medium. However,the Surgeon can be located in a different room, a completely differentbuilding, or other remote location from the Patient allowing for remotesurgical procedures (i.e., operating from outside the sterile field).

FIG. 3 is a perspective view of the Electronics Cart 24. The ElectronicsCart 24 can be coupled with the endoscope 28 and can include a processorto process captured images for subsequent display, such as to a Surgeonon the Surgeon's Console, or on any other suitable display locatedlocally and/or remotely. For example, where a stereoscopic endoscope isused, the Electronics Cart 24 can process the captured images so as topresent the Surgeon with coordinated stereo images of the surgical site.Such coordination can include alignment between the opposing images andcan include adjusting the stereo working distance of the stereoscopicendoscope. As another example, image processing can include the use ofpreviously determined camera calibration parameters so as to compensatefor imaging errors of the image-capture device, such as opticalaberrations.

FIG. 4 diagrammatically illustrates a robotic surgery system 50 (such asMIRS system 10 of FIG. 1). As discussed above, a Surgeon's Console 52(such as Surgeon's Console 16 in FIG. 1) can be used by a Surgeon tocontrol a Patient-Side Cart (Surgical Robot) 54 (such as Patent-SideCart 22 in FIG. 1) during a minimally-invasive procedure. ThePatient-Side Cart 54 can use an imaging device, such as a stereoscopicendoscope, to capture images of the procedure site and output thecaptured images to an Electronics Cart 56 (such as the Electronics Cart24 in FIG. 1). As discussed above, the Electronics Cart 56 can processthe captured images in a variety of ways prior to any subsequentdisplay. For example, the Electronics Cart 56 can overlay the capturedimages with a virtual control interface prior to displaying the combinedimages to the Surgeon via the Surgeon's Console 52. The Patient-SideCart 54 can output the captured images for processing outside theElectronics Cart 56. For example, the Patient-Side Cart 54 can outputthe captured images to a processor 58, which can be used to process thecaptured images. The images can also be processed by a combination theElectronics Cart 56 and the processor 58, which can be coupled togetherso as to process the captured images jointly, sequentially, and/orcombinations thereof. One or more separate displays 60 can also becoupled with the processor 58 and/or the Electronics Cart 56 for localand/or remote display of images, such as images of the procedure site,or any other related images.

FIGS. 5A and 5B show a Patient-Side Cart 22 and a surgical tool 62,respectively. The surgical tool 62 is an example of the surgical tools26. The Patient-Side Cart 22 shown provides for the manipulation ofthree surgical tools 26 and an imaging device 28, such as a stereoscopicendoscope used for the capture of images of the site of the procedure.Manipulation is provided by robotic mechanisms having a number ofrobotic joints. The imaging device 28 and the surgical tools 26 can bepositioned and manipulated through incisions in the patient so that akinematic remote center is maintained at the incision so as to minimizethe size of the incision.

Images of the surgical site can include images of the distal ends of thesurgical tools 26 when they are positioned within the field-of-view ofthe imaging device 28.

Mounting and Demounting of a Bound Surgical Tool

FIGS. 6 and 7 illustrate the coupling of an interface fitting 64 coupledand a frame 66 of a proximal chassis of a robotic surgical tool for aminimally invasive robotic surgery system, in accordance with manyembodiments. The interface fitting 64 has a u-shaped configuration thatinterfaces with the frame 66 on three sides of the frame. The interfacefitting 64 includes first and second elongate flanges 68, 70 disposed onopposite sides of the interface fitting. The first and second elongateflanges 68, 70 are received within complementary shaped slots 72, 74,respectively, disposed on corresponding opposite sides of the frame. Theinterface fitting is coupled with the frame by sliding the first andsecond elongate flanges 68, 70 into the corresponding slots 72, 74 andinstalling two removable fasteners 76 to secure the interface fitting tothe frame, thereby preventing relative axial sliding between theinterface fitting and the frame. The frame includes two receptacles 78configured to receive and rotationally restrain two nuts 80 for the tworemovable fasteners 76.

The interface fitting 64 provides mounting features that are receivableby a holding fixture of a robotic manipulator of a minimally invasivesurgical system. The mounting features include two external flanges 82,84 disposed on opposite sides of the interface fitting and configured tobe received by respective complementary-shaped slots in the holdingfixture of the robotic manipulator.

FIGS. 8 and 9 illustrate mounting and demounting of a surgical tool 86to and from, respectively, a robotic manipulator 88 of a minimallyinvasive surgical system, in accordance with many embodiments. In FIG.8, the interface fitting 64 is shown coupled with the frame of theproximal chassis 90, and the combined assembly is mounted to a holdingfixture 92 of the robotic manipulator 88. In normal circumstances, theinterface fitting can be coupled to the frame and the combined assemblycan then be mounted to the holding fixture by inserting a distal end 94of the surgical tool through a guide aperture 96 of the roboticmanipulator 88 and mounting the combined assembly onto the holdingfixture via relative sliding between the combined assembly and theholding fixture along a direction corresponding to receiving slots 98 inthe holding fixture and the two external flanges 82, 84 of the interfacefitting. Likewise, in regular circumstances, the combined assembly canbe demounted from the holding fixture via a reverse relative slidingbetween the combined assembly and the holding fixture. A securingfeature (not shown) can be used to selectively prevent relative slidingbetween the mounted combined assembly and the holding fixture so thatthe combined assembly is fully secured to the holding fixture 92.

FIG. 9 illustrates demounting the surgical tool from the roboticmanipulator in response to binding of the surgical tool 86 within asurgical site so as to inhibit the removal of the surgical tool from thesurgical site and disengagement of the combined assembly from theholding fixture of the robotic manipulator. By removing the tworemovable fasteners 76 (shown in FIGS. 6 and 7), the interface fittingcan be decoupled from engagement with both the frame 66 and the holdingfixture 92, thereby decoupling the frame 66 from the holding fixture 92.The robotic manipulator 88 can then be moved out of the way, therebyproviding increased access to the bound surgical instrument.Accordingly, a surgical instrument can be decoupled from a roboticmanipulator when an end effector clamping device is unable to beunclamped from patient tissue while the surgical instrument is fullyinserted into the patient. Likewise, this demounting process can bereversed to mount a surgical instrument to the robotic manipulator.

FIG. 10 illustrates a method 100 for using a surgical instrument with arobotic manipulator of a minimally surgical system, in accordance withmany embodiments. The surgical tools and interface fittings disclosedherein can be used to practice the method 100.

In act 102, a surgical tool is provided that includes a proximal chassishaving a frame, an interface fitting coupled with the frame, and asecuring feature to prevent relative movement between the interfacefitting and the frame. For example, the surgical tool can include anelongate shaft extending along an axis between a distal end and aproximal end, the proximal chassis, and an end effector disposed at thedistal end. The interface fitting can be demountably coupled with theframe via sliding engagement along the axis between the frame and theinterface fitting. The sliding engagement can be provided viacomplementary-shaped interfacing features on the interface fitting andthe frame, such as a slot extending along the axis. For example, thecomplementary-shaped interfacing features of the frame can include twoslots extending along the axis that are disposed on opposite sides ofthe frame. The complementary-shaped interfacing features of theinterface fitting can include two protruding features, such as flanges,extending along the axis. And the securing feature can be operable toprevent relative axial sliding between the interface fitting and theframe. The securing feature can include one or more removable fasteners.

In act 104, the chassis is mounted onto a holding fixture of the roboticmanipulator. For example, a mounting feature of the interface fittingcan be engaged with a complementary-shaped mounting feature of theholding feature.

In act 106, the end effector is manipulated within a minimally invasivesurgical site. For example, the end effector can be a cutting andstapling device that is used to resect a cancerous tissue.

In act 108, in response to binding of the surgical tool within thesurgical site, the securing feature is released so as to allow relativesliding between the interface fitting and the frame. Such binding mayinhibit removal of the end effector and shaft from the surgical site andinhibit disengagement of the mounting feature of the interface fittingfrom the mounting feature of the holding fixture.

In act 110, the frame, shaft, and end effector of the surgical tool isdemounted from the interface fitting of the surgical tool and theholding fixture of the robotic manipulator by moving both the interfacefitting and the holding fixture relative to the frame along the axis.

The method 100 can include additional acts. For example, the method canfurther include sliding the interface fitting into engagement with theframe. And the method 100 can further include securing the interfacefitting in engagement with the frame via the securing feature.

Other variations are within the spirit of the present invention. Thus,while the invention is susceptible to various modifications andalternative constructions, certain illustrated embodiments thereof areshown in the drawings and have been described above in detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

What is claimed is:
 1. A method for using a surgical instrument with arobotic manipulator of a minimally invasive surgical system, the methodcomprising: providing the surgical instrument, the surgical instrumentincluding: an elongate shaft extending along an axis between a distalend and a proximal end; a chassis disposed at the proximal end, thechassis including a frame, an interface fitting demountably coupled withthe frame via sliding engagement along the axis between the frame andthe interface fitting, and a securing feature that is operable toprevent relative axial sliding between the interface fitting and theframe; and an end effector disposed at the distal end; mounting thechassis onto a holding fixture of the robotic manipulator by engaging amounting feature of the interface fitting with a complementary-shapedmounting feature of the holding fixture; articulating the end effectorwithin a minimally invasive surgical site; in response to binding of thesurgical instrument within the surgical site so as to inhibit removal ofthe end effector and shaft from the surgical site, and so as to inhibitdisengagement of the mounting feature of the interface fitting from themounting feature of the holding fixture, releasing the securing featureso as to allow relative sliding between the interface fitting and theframe; and demounting the frame, shaft, and end effector of the surgicalinstrument from the interface fitting of the surgical instrument and theholding fixture of the robotic manipulator by moving the interfacefitting relative to the frame along the axis.
 2. The method of claim 1,further comprising: sliding the interface fitting into engagement withthe frame; and securing the interface fitting in engagement with theframe via the securing feature.
 3. The method of claim 1, wherein thesecuring feature comprises a removable fastener.
 4. The method of claim3, wherein the securing feature comprises a plurality of removablefasteners.
 5. The method of claim 1, wherein the interface fitting andthe frame comprise complementary-shaped interfacing features thatinclude a slot extending along the axis.
 6. The method of claim 5,wherein the complementary-shaped interfacing features of the interfacefitting and the frame comprise two slots extending along the axis, theslots disposed on opposite sides of the frame.
 7. The method of claim 6,wherein the frame includes the two slots and the interface fittingincludes two protruding mounting features extending along the axis. 8.The method of claim 7, wherein each of the protruding mounting featurescomprises a flange extending along the axis.
 9. A surgical instrumentfor use with a robotic manipulator of a minimally invasive surgicalsystem, the robotic manipulator having a holding fixture, the surgicalinstrument comprising: an elongate shaft extending along an axis betweena distal end and a proximal end; a chassis disposed at the proximal endof the shaft, the chassis including: a frame holding the shaft, aninterface fitting demountably coupled with the frame and the holdingfixture via sliding engagement along the axis between the frame and theinterface fitting, the interface fitting having a mounting featurereceivable by the holding fixture of the robotic manipulator so as tomount the instrument thereon, the frame and the interface fittingtogether comprising complementary-shaped interfacing features thatinclude a slot extending along the axis, and a securing featurereleasably preventing relative axial sliding between the interfacefitting and the frame; and an end effector disposed at the distal end ofthe shaft, the end effector articulatable relative to the shaft so as tomanipulate tissue within a minimally invasive surgical site, thesecuring feature configured for releasing in response to binding of thesurgical instrument within the surgical site, the binding inhibitingremoval of the end effector and the shaft from the surgical site anddisengagement of the mounting feature of the interface fitting from theholding fixture, releasing of the securing feature allowing relativesliding between the interface fitting and the frame so as to promotedemounting the frame, the shaft, and the end effector of the surgicalinstrument from the interface fitting of the surgical instrument and theholding fixture of the robotic manipulator by moving the interfacefitting relative to the frame along the axis, wherein, upon releasing ofthe securing feature, the interface fitting can be demounted before theframe is demounted from the holding fixture.
 10. The surgical instrumentof claim 9, wherein the securing feature comprises a removable fastener.11. The surgical instrument of claim 10, wherein the securing featurecomprises a plurality of removable fasteners.
 12. The surgicalinstrument of claim 9, wherein the complementary-shaped interfacingfeatures of the frame and the interface fitting comprise two slotsextending along the axis, the slots disposed on opposite sides of theframe.
 13. The surgical instrument of claim 12, wherein thecomplementary-shaped interfacing features of the frame includes the twoslots and the complementary-shaped interfacing features of the interfacefitting includes two protruding mounting features extending along theaxis.
 14. The surgical instrument of claim 13, wherein each of theprotruding mounting features comprises a flange extending along theaxis.
 15. The surgical instrument of claim 9, wherein the interfacefitting has a u-shaped configuration that interfaces with the frame onthree sides of the frame.
 16. The surgical instrument of claim 15,wherein the interface fitting is received within the slot extendingalong the axis.
 17. The surgical instrument of claim 16, wherein thesecuring feature comprises two removable fasteners, each of theremovable fasteners coupling with a nut retained by the frame.